Mammographic findings of women recalled for diagnostic work-up in digital versus screen-film mammography in a population-based screening program.

BACKGROUND: Limited information is available concerning differences in the radiological findings of women recalled for diagnostic work-up in digital mammography (DM) versus screen-film mammography (SFM) screening.
PURPOSE: To compare the radiological findings, their positive predictive values (PPVs) for cancer and other process indicators of DM screening performed by computed radiography (CR) technology and SFM screening in a population-based program.
MATERIAL AND METHODS: The material consisted of women, 50-59 years of age, who were invited for screening: 30 153 women with DM in 2007-2008 and 32 939 women with SFM in 1999-2000. The attendance rate was 77.7% (23 440) in the DM arm and 83.8% (27 593) in the SFM arm. In the DM arm, 1.71% of those screened (401) and in the SFM arm 1.59% (438) were recalled for further work-up. The images resulting in the recall were classified as: 1) tumor-like mass, 2) parenchymal distortion/asymmetry, 3) calcifications, and 4) combination of mass and calcifications. The distributions of the various radiological findings and their PPVs for cancer were compared in both study groups. The recall rates, cancer detection rates, test specificities, and PPVs of the DM and SFM groups were also compared.
RESULTS: Women were recalled for diagnostic work-up most often due to tumor-like mass. It was more common in SFM (1.08% per woman screened) than in DM (0.93%). The second most common finding was parenchymal distortion and asymmetry, more often in DM (0.58%) than in SFM (0.37%). Calcifications were the third most common finding. DM exposed calcifications more often (0.49%) than SFM (0.26%). The PPVs for cancer of the recalls were higher in DM than in SFM in all subgroups of radiological findings. The test specificities were similar (DM 98.9%, SFM 98.8%). Significantly more cancers were detected by DM (cancer detection rate 0.623% per woman screened, n=146) than by SFM (cancer detection rate 0.406% per woman screened, n=112). The PPVs for cancer of all recalls for diagnostic work-up were significantly higher in DM (36%) than in SFM (26%).
CONCLUSION: In DM women were recalled for diagnostic work-up more often for calcifications, parenchymal distortions, and asymmetries than in SFM. In the case of tumor-like masses, more women were recalled in SFM. DM detected more cancers than SFM, and the PPVs for cancer were higher in DM than in SFM in all subgroups of radiological findings.